What is an Impact Driver & When Do You Need One?

Impact drivers are used for drilling holes and fastening screws, bolts and nuts into a surface. They are common tools for handymen, woodworkers and construction workers.

However, an impact driver is easily confused with other power tools. At first glance they might look the same as a hammer drill or impact wrench but these tools all perform different functions.

Find out all you need to know about impact drivers, what they do and when to use one in this handy guide. We cover all the information you need to know to find the best impact driver for you. If you already know what you’re looking for, check out our top 10 impact drivers list to compare products and find the right one for your project!

Table of Contents

Basic Information & What to Look for

HOW DOES AN IMPACT DRIVER WORK

An impact driver creates holes in surfaces to make it easier to get in a nail, screw or bolt. They are also used for tightening a nail, screw or bolt.

This tool is known for how powerful it is, more powerful than a regular drill. That is why for tougher materials or when the nail needs to go in deeper, this impact drill is used.

The reason why an impact drill is more powerful can be found in its mechanics. Essentially, it combines a fast rotational force with a hammering force.

In addition to a shaft and drill bit which you see rotating there is a spring, hammer and anvil inside the tool. The motor powers the shaft and when the shaft rotates it causes the spring to compress.

The spring is then released again which triggers the hammer and anvil causing an extra ‘impact’. So, in addition to the rotational force of the shaft there is the stronger force of the hammer and anvil at the same time.

The secondary force from the hammer and anvil is indirect, it does not pound directly unto shaft. Rather, it creates a greater force around the shaft when it starts to slow down – think of it as kicking into a higher gear.

The combination of these two forces is what makes an impact driver more powerful than a regular drill. In practice, this means that an impact drill can push through faster and deeper.

However, this mechanism only kicks in when the tool senses that extra force is needed. When there is little resistance it only produces the rotational force, also referred to as torque.

This is why impact drivers are considered so versatile. It is like working with a regular drill when the surface is easy to get through but has backup power whenever needed.

Impact Drivers Vs. Cordless Drills

DIFFERENCES BETWEEN CORDLESS DRILLS & IMPACT DRIVERS

Cordless impact drivers are often compared to cordless drills because they have a similar function and often have a similar design. However, there are key differences between them.

In other words, an impact driver produces both torque and a hammering force while a cordless drill only applies torque.

Other differences are in the general design. Compared to a cordless drill, an impact driver tends to be smaller in size and more lightweight, despite the extra force.

The final difference depends on the specific models but generally rings true. Most cordless drills have a chuck while impact drivers have a hex drive system which limits the type of bits that can be connected for both tools.

It is better to use a cordless drill when working on softer surfaces or when you don’t need as much power for loosening or tightening screws. In other words, the impact driver is more of a heavy duty tool.

Impact Drivers Vs. Hammer Drills

DIFFERENCES BETWEEN HAMMER DRILLS & IMPACT DRIVERS

A hammer drill is similar to an impact driver in the way that it as a secondary pounding force in addition to the torque. However, that secondary pounding force works differently.

There are several different kinds of hammer drills but their main purpose remains the same: drilling holes into hard surfaces such as rock, concrete and tiles. Unlike an impact driver they are not suitable for tightening screws and bolts.

Impact Drivers Vs. Impact Wrenches

DIFFERENCES BETWEEN IMPACT WRENCHES & DRIVERS

Both of these tools use a combination of torque and a hammering force but they are used for different purposes. There are two main differences between an impact driver and an impact wrench that explain why.

These two differences make an impact wrench better equipped at loosening or fastening sockets. The shape of the drive does not fit so well on screws, nails and bolts.

Impact wrenches therefore have a much more limited use. You are most likely to find them in a professional automobile workshop where they are often used for work on tires.

When to Use an Impact Driver

Compared to cordless drills, impact wrenches and hammer drills, an impact driver is more versatile. Even for tasks that these tools could be used interchangeably, there are several advantages to having an impact driver in your toolbox.

Impact drivers are the best choice when working with fasteners, whether it is to loosen or tighten them. They also have enough power for getting screws, nails and bolts into tougher materials and deeper settings.

Woodworkers and construction workers will get a lot of use out of these tools as they are quite versatile. DIY enthusiasts might also want to have them available when they know they are going to work with hard materials or refurbishing furniture.

Advantages & Disadvantages of Impact Drivers

ADVANTAGES

Generally, impact drivers are very user-friendly because of their design and how their power is released. However, no tool is perfect so there are a few drawbacks to using them, as well.

The first perk of picking up this tool is that they are generally lightweight and compact. They are designed to fit into small spaces and at awkward angles so their maneuverability is excellent.

The second benefit is how they are less likely to cause fatigue. Thanks to how it mechanically functions there is limited kickback and resistance which lightens the pressure and vibrations on your hands.

With limited kickback and resistance it is also easier to maintain control over an impact driver. Bonus points are given to impact drivers with a one-handed design which are even more comfortable to work with.

DISADVANTAGES

The main disadvantages of impact driver is the initial cost. A good model costs around $100 when you want it complete with compatible bits.

Bare tool options might cost less and the more complete sets will cost more. So, there is some flexibility in the price but they are not necessarily the most affordable tool in your toolbox.

One way you can save more money is by choosing a brand that you already have several battery-powered tools from. Most impact drivers are compatible with the universal batteries of the same brand so you can use the same battery for several tools.

Terms to Know Before Buying

IPM

IPM stands for Impacts Per Minute and refers to the number of times the hammer and anvil inside the impact driver hit. The IPM rating of an impact driver is indicative of how powerful the tool is.

The higher the IPM value the more powerful the tool because it essentially means that it applies the additional force more often. Thus, the higher the IPM the faster it can drive through hard materials.

3000 IPM is standard but it is not necessary for every job. For DIY projects anywhere between 2400 – 3000 IPM might already be enough while for more professional and heavy duty jobs you should consider going higher than 3000 IPM.

IPM in Relation to Torque

Torque describes power and with impact drivers this power is usually expressed in either inch-pounds (imperial) or Newton-meters (Metric). The higher the value the more powerful the tool.

IPM and torque are often mentioned in relation to each other when describing impact drivers. This is because the IPM has a strong influence on the overall power.

For example, a model with average torque might still be considered powerful if it has a higher IPM. That is why it is useful to know the values of both when deciding how suitable the tool is for the type of tasks you will be using it for.

The standard torque is around 1400 – 1600 inch/pounds. It is not recommended to opt for anything less than 1400 in/lbs unless you are performing very minor tasks but professionals will want a tool capable of 1800 or more in/lbs.

RPM

RPM stands for Rotations Per Minute and refers to how many times the shaft completes a full spin within a minute. It is also referred to as the speed of the power tool.

RPM has less influence on the actual power of the tool and is more important to know when you plan on using the impact driver for drilling. If you have used a regular drill before, you will know that control over the speed is important.

Thus, choose an impact driver that has variable speed capabilities. This will give you the most control.

What to Look for When Buying an Impact Driver

Besides the IPM, torque and RPM, there are other important features to consider when shopping for an impact driver. These are the chuck size, the battery, whether it has a light and the overall comfort of the design.

Chuck size

As mentioned, most units have the standard chuck size of 1/4 inch. What is more important is to check how you can change the bits.

A keyless or fast release chuck is preferable since this lets you switch out bits the fastest. A keyless chuck does a lot for efficiency and is especially useful for construction workers that might need to replace the bit while standing on tall ladders.

Battery

The battery is very important because it influences how much power the tool has and how long you can keep working. The standard batteries are either 18 volt or 20 volt but the battery life is actually more important.

Check what the Amp hours (Ah) are of the unit and check the reviews for what users say is the average time that the battery lasts. It is also smart to have at least 2 compatible batteries so you can quickly switch them out when one runs out of charge.

Light

This might seem like a small detail but it makes a lot of difference while you are working. You would be surprised how big of a shadow you are creating or how much easier it is to focus when you have an LED light on the unit.

Luckily, an LED light is quite a standard feature. There are also models with a more advanced tri-beam LED light.

Overall Design Comfort

Finally, we get to the dimensions, weight and design details of impact drivers. Most models are already more lightweight and compact than similar tools but there are more design details to consider.

A textured rubberized grip is best because this gives you a firmer grasp on the tool. You also want an ergonomic design, especially if you will be working in odd crevices and angles.

In short, impact drivers are great tools for when you need a little more power when drilling and fastening but don’t want to compromise on comfort and size. Impact drivers are great assets for construction work, carpenters and even DIY enthusiasts.